Vendor Evaluation Standardizing Delivery Date Variance

Hi,

We are determining what the settings should be for On-Time Delivery and Quantity Reliability under Vendor Evaluation.  I understand how the formual works when it determines the scores for these.  Can someone tell me from a business process perspective what Standardizing Delivery Date Variance relates to? 

Ours has been set to 100 which is 100 days with the scores set as:

When we pick 100 days, is that supposed to be an average of how many days late goods receipts are?  Or is there another way to look at it? 

Thanks

Beverly